This invention relates generally to cardiac pacing and mapping systems used in diagnosing and treating cardiac conditions. The invention also relates to electronic switching systems for programmably intercoupling multiple inputs with multiple outputs in pre-selected configurations. More particularly, the invention relates to an application specific integrated circuit (ASIC) operable to configure multiple input electrodes for cardiac signal recording and analysis or stimulation based on the immediate necessities of a particular electrophysiological procedure.
Advances in the cardiac mapping and pacing art have made it possible to acquire cardiac data through multiple channels. Known cardiac mapping and pacing catheters contain as many as sixty-four individual electrodes, each of which can be used for both mapping and pacing. Along with the flexibility, resolution and utility provided by such catheters comes the need to process the resulting data in an efficient, organized manner.
Various data acquisition systems have been developed for processing data acquired during cardiac mapping and pacing procedures. Typically, such systems record data through multiple recording inputs and process the data to assist the physician in making a diagnosis and rendering treatment. Some systems also include circuitry for generating pacing pulses that can be applied to the heart. Although effective in their intended application, known data acquisition systems become limited in their capabilities as advances in cardiac catheters provide ever increasing amounts of data. Many known data acquisition systems only support input from up to twenty-four electrodes and are not directly useful with catheters containing more than twenty-four electrodes. Because data acquisition systems are larger, more complicated and more expensive than the cardiac catheters used in mapping and pacing, it is impractical to redesign a data acquisition system each time an advance in the catheter art enables the acquisition of still more data. Nor is it economically sound for health care providers to retire still serviceable existing systems in favor of the latest model each time a new catheter is introduced. As advances are made in the catheter art, a need develops for adapting the new catheter to use with existing data acquisition systems.
The advances that can increase the demands on a data acquisition system are many and varied. For example, xe2x80x9cimpedance mappingxe2x80x9d techniques have been developed wherein the resistivity of cardiac tissue is measured using an injected current. Infarcted cardiac tissue is detected by virtue of the lower electrical resistivity such tissue displays relative to healthy or normal tissue. Known data acquisition systems do not provide for the flexible electrode configuring and sequencing required or desirable in impedance mapping procedures. Similarly, existing data acquisition systems do not provide for automated sequencing and configuration of pacing electrodes. Nor do such systems provide for automatic detection of open or shorted electrodes. As the number of electrodes used in a procedure increases, so does the possibility of such malfunctions. Existing systems do not automatically and continuously monitor the electrodes to warn the physician in the event some of the electrodes are open or shorted. Absent an appropriate warning that some electrodes are no longer suitable for therapy or diagnosis, the delivery of effective therapy can be unknowingly prevented.
Known data acquisition systems for recording electrophysiological (EP) information have previously achieved switching capability through use of analog switch chips or mechanical switches in the system""s signal conditioning circuitry. The ability to increase the number of potential electrode inputs was dependent on the particular system. Prior data acquisition systems were not designed for use with catheters containing large numbers of electrodes and did not provide the flexibility for configuring electrode subsets. Such prior systems also lacked open/short detection and automated pacing/switching capabilities.
The invention provides an application specific integrated circuit (ASIC) having a plurality of inputs, a plurality of outputs, a cross point switch matrix coupled to the inputs and to the outputs, and a control circuit coupled to the cross point switch matrix for controlling the cross point switch matrix to couple selected ones of the inputs with selected ones of the outputs in accordance with applied commands.
The invention also provides an ASIC operable to couple biological signals sensed by a plurality of biological electrodes with a plurality of input channels of an biological recorder. The ASIC includes a plurality of inputs operable to receive the biological signals sensed by the biological electrodes and a plurality of outputs that can be coupled to individual ones of the input channels of the biological recorder. The ASIC further includes a cross point switch matrix coupled to the inputs and the outputs. The ASIC further includes a control circuit coupled to the cross point switch matrix for controlling the cross point switch matrix to couple selected ones of the inputs with selected ones of the outputs in accordance with applied commands and thereby direct the biological signals sensed by selected ones of the biological electrodes with selected ones of the biological recorder input channels.
The invention also provides an ASIC operable to couple biological signals sensed by a plurality of biological electrodes with a plurality of input channels of an biological recorder. The ASIC includes a plurality of input operable to receive the biological signals sensed by the biological electrodes, a plurality of outputs that can be coupled to individual ones of the input channels of the biological recorder, a cross point switch matrix coupled to the inputs and to the outputs, an edge detector coupled to the cross point switch matrix and operable to detect the edges of applied electrical pulses, an edge counter coupled to the edge detector, test circuitry coupled to the cross point switch matrix operable to detect shorted and open conditions in the biological electrodes, and a control circuit coupled to the cross point switch matrix, the edge detector, the edge counter and the test circuitry for controlling the cross point switch matrix to couple selected ones of the inputs with selected ones of the outputs in accordance with applied commands and thereby direct the biological signal sensed by selected ones of the biological electrodes with selected ones of the biological recorder input channels.
It is an object of the invention to provide a new and improved interface system for coupling a number of cardiac electrodes to an biological recorder having the same number or fewer input channels than the number of electrodes.
It is a further object of the invention to provide an interface system that provides complete flexibility in the possible connections between the available inputs and available outputs.
It is a further object of the invention to provide an interface system that permits bi-directional transfer of signals between the available inputs and the available outputs.
It is a further object of the invention to provide an interface system that provides for pacing through the electrodes using externally generated stimulator pulses.
It is a further object of the invention to provide an interface system that provides pace pulse detection, counting and sequencing for particular diagnostic procedures.
It is a further object of the invention to provide an interface system that provides appropriate in-out connectivity for impedance mapping based on four or two electrode methods.
It is a further object of the invention to provide an interface system that automatically detects abnormal operating conditions such as open or shorted electrodes.
It is a further object of the invention to provide an interface system that automatically identifies the electrodes and biological recorder channels and that automatically verifies proper lead connections.
It is a further object of the invention to provide an interface that can be operated via an external, microprocessor-based control system.
It is a further object of the invention to provide an interface that compensates for pacing overvoltages and resulting polarization overpotentials so as to avoid biological recorder saturation.
It is a further object of the invention to avoid the saturation of a biological recorder by providing an interface that decouples pacing inputs from recorder outputs based on comparison with a threshold.
It is a further object of the invention to avoid the saturation of a biological recorder by providing an interface that decouples pacing inputs from recorder outputs based on ascertaining the pacing rate and/or pulse duration.
It is a further object of the invention to avoid the saturation of a biological recorder by providing an interface that decouples pacing inputs from recorder outputs based on analysis of pacing pulse derivative.
It is a further object of the invention to avoid the saturation of a biological recorder by providing an interface that connects decoupled outputs to known voltages.
It is a further object of the invention to avoid the saturation of a biological recorder by providing an interface that uses adaptive filtering removal of paced-induced voltages.
It is a further object of the invention to provide an interface that can be implemented in the form of an application specific integrated circuit (ASIC).